In a distributed computer network, such as a fibre channel-to-SCSI router architecture, one interface, such as a SCSI router, can communicate with a plurality of target devices on behalf of a plurality of initiators, such as host devices, attached to the fibre channel. In this arrangement the router provides a pass-through data management role. That is, the target device is transparent to the initiator sending a command, and likewise the host is transparent to the target sending a signal.
In this pass-through management role, one thing the router does is receive unit attention signals from the target device and send them to all the initiators in the network. A unit attention signal communicates information about the current status of the target. Generally, the target sends a unit attention signal after going through some change in status of which the initiator will benefit in knowing as part of its operational sequencing. For example, a unit attention signal might be sent if the target has undergone a power-on sequence, or if a reserve relationship has been interrupted, or if a code change has occurred affecting the initiator-target relationship or status.
Where there are multiple initiators in the network, it is important that the unit attention signal be communicated to each and every initiator. However, only one unit attention signal can be processed for each command from the target to the initiator in a SCSI network. Accordingly, some attempted solutions employ using registers and associated code to record the event of a target having a pending unit attention signal, as well as other registers to record which of the plurality of initiators have received the pending unit attention signal. Such solutions involve complex programming steps that are cumbersome to modify, such as when it is desireable to change or add to the conditions that warrant the unit attention signal be sent. Also, such solutions are not readily adaptable to storing and subsequently sending multiple prioritized unit attention signals.